Load bearing structure for composite ecological shipping pallet

ABSTRACT

A shipping pallet typically consists of a solid deck or slats and runners arranged to provide a top surface and legs or posts to provide open access underneath for a forklift type device and is used to store and/or transport a variety of products.  
     The composite ecological shipping pallet of the present invention offers significant advantage over present state of the art in the field. It is stronger, lighter, stiffer and more rigid, more economical, and ecologically sound.  
     The present invention features a combination of design elements that utilize the most effective geometric shapes to increase strength and reduce weight. It allows manufacture from a multitude of potential materials and even allows combinations of different materials within the same component so as to enhance desirable features.  
     With the above stated improvements in the art, the present invention satisfies a need in the marketplace and materially effects world commerce a nd preservation of the ecology.

REFERENCE

[0001] Reference prior U.S. patent application Ser. No. 09/863,620—Filing Date May 23, 2001

[0002] Disclosure Document No. 495799—Filing Date Jun. 19, 2001

[0003] Disclosure Document No. Pending—Filing Date Aug. 02, 2001

[0004] There has been no federally funded sponsored research or development of the present invention.

[0005] There is no Microfiche Appendix to this application for letters patent on the present invention.

BACKGROUND OF THE INVENTION

[0006] Shipping pallets are used as portable platforms to handle, store and transport loads consisting of food, beverage, and most every product or product component produced. The world market exceeds 1.5 billion pallets sold annually with the United States alone accounting for half a billion sales.

[0007] A pallet is typically made of wood and consists of slats and posts arranged to provide a top surface and open access underneath for a fork lift type device. Bottom slats may also be added to provide for transport on conveyer belts, for use in automated machinery, and to add strength, stiffness and rigidity to the pallet.

[0008] Present shipping pallets are usually constructed of wood or wood products with numerous associated problems. There are few shipping pallets constructed from alternative materials, but no matter what construction material used, all present shipping pallets suffer from one or more significant problems, some of which are described herein.

[0009] Construction material choice has unintended consequences that significantly impact the end user and the world at large. Wooden pallets are heavy and often present rough and/or broken areas leading to work related injuries such as muscle strain, hernia, splinters or worse, and damage to the product being transported.

[0010] Ignoring the obvious issues surrounding logging, there are ecological issues now being addressed globally. Wooden pallets play host to a wide variety of entomological pests and, as a consequence, introduce non-native species of destructive pests into foreign ecology systems. This problem has recently been recognized, and numerous countries around the world are enacting regulations to address it. Even more regulatory action is proposed, and international treaties, along with trade barriers against untreated wooden pallets, are already in force. The cost of wooden shipping pallets can only increase dramatically as preventative and safety measures now mandated are enforced.

[0011] One preventative action taken is the application of pesticides. Another preventative action is baking the wood material. Application of pesticides introduces the risk of contaminating the product being carried on the shipping pallet. Baking the wood increases the cost of the shipping pallet and still doesn't address the issue of subsequent entomological infestation. Baking also dries out the wood, which increases fire danger. Baking also increases the danger of splinters and the inevitable injury to workers using the pallet.

[0012] Disposal of wooden shipping pallets is an equally compelling problem. In the United States alone there are some 270 million wooden shipping pallets sent to landfills or burned yearly. Burning wooden pallets contributes to atmospheric pollution. With current and proposed entomological safeguards mandating pesticide treatment, the problem of pallet disposal becomes even more critical. The added factor of pesticide residue leaching into ground water or being released into the atmosphere through combustion exacerbates the problem. There have even been instances of pesticide treated wood pallets contaminating the product they carry.

[0013] The present invention provides significant improvement to the art of shipping pallet strength, weight, stiffness and rigidity, cost, design, versatility, production, transport, storage, reuse and recyclability, and ecological acceptability. Prior art amply demonstrates the attention inventors have paid to at least a few of these issues. U.S. Pat. Nos. 5,170,722; 5,365,859; 5,402,735; 5,417,167; 5,456,189; 5,497,709; 5,601,035; and 5,941,179 disclose various designs for prior art pallets.

[0014] U.S. Pat. No. 5,417,167 describes a modular plastic pallet design but falls short of the present invention in that the “deck boards” attachment method optionally requires added fasteners and reacts badly to the imposition of a unit load by loosening their grip or attachment to the “stringers.” It also describes a design that is decidedly weaker than the present invention and displays a lack of planar stiffness and rigidity that is overcome by the present invention.

[0015] U.S. Pat. No. 5,941,179 describes a modular plastic pallet design comprising two basic components that may be assembled into a variety of different pallet configurations to meet specific user needs. The runner to slat attachment means is weak, and the stiffness and rigidity of the design is less than that of the present invention. As with U.S. Pat. No. 5,417,167, this design is amenable to manufacture from a variety of raw materials, including thermoplastics, to eliminate the problem of wood pest hosting.

BRIEF SUMMARY OF THE INVENTION

[0016] The present invention adds a number of novel and unique features to shipping pallet art. Utilizing the present invention, shipping pallets can be manufactured mostly from recyclable materials. They can be manufactured from materials that do not support entomological infestation and that can be fire retarding. Structural load bearing characteristics of shipping pallets are enhanced through the utilization of an internal or exoskeleton of a high strength, lightweight material. Durability and impact resistance of the entire pallet structure is enhanced with the use of a suitable inner and/or outer form of a more ductile material. The shipping pallet is built as a compound structure so as to take advantage of varying shapes, sizes, materials and component arrangements to enhance strength, stiffness and rigidity, weight, entomological infestation resistance, fire resistance, and other physical characteristics. The composite design is suitable for any size or configuration of shipping pallet. It is stronger, lighter and more rigid than present shipping pallets. It is reusable for many service cycles, and then it is recyclable at the end of its useful life.

DRAWING FIGURES

[0017]FIG. 1 illustrates a preferred embodiment of the present invention. In View a, item 1 is a structural skeleton, which may be internal or external to the product it enhances. Item 2 is a plurality of hemispherical elements whose function is later fully explained. Item 3 is a plurality of tubular or semi-tubular terminators whose function is later fully explained. View b is the exploded upper right hand corned of View a. In View b items 2 and 3 are shown in greater detail. View c shows the structural skeleton of the present invention incorporated into a casing to provide a form factor to the enhanced product, which in this illustration is a shipping pallet. View d shows how the fill material is used to provide form factor to the end product by encasing present invention structural skeleton; view d includes detail views of items 2 and 3. View e is the completed end product with the structural skeleton of the present invention contained within.

[0018]FIG. 2, item 4 illustrates a representative pallet deck as a beam that is supported on posts or legs and provides background information for purposes of further describing the advantages of the present invention. Item 5 is a beam loaded on the top and deflecting downward. This loading places the upper fibers of the beam into compression and the lower fibers of the beam into tension. Materials exhibit better physical properties in compression than in tension, so the failure mode for a typical beam is rupture in tension beginning at the lower fibers.

[0019]FIG. 3a shows a full arch and FIG. 3b shows an arch of the present invention. A full arch transmits applied force parallel to the force, displacing the force to the outermost section of the arch, as shown in FIG. 3a. An arch that is terminated short of the centerline transmits an applied force at some angle to the force, depending upon the geometry of the arch.

[0020]FIG. 4a shows the arch elements, item 7, of the present invention in contact at the outer edges. A force that is applied to these arches is transmitted through the arches to the contact point, item 8, thereby creating a compressive force at the contact point. FIG. 4b shows that the probable failure mode is in tension in the lower fibers of the beam or pallet deck. FIG. 4c shows how the present invention creates a countervailing compressive stress in the lower fibers of the beam or pallet deck to fully or partially offset the tensile stresses created by the bending moment and by redirecting stress inducing forces laterally to be absorbed by the edge tubular and/or semi-tubular supports, which are shown in FIG. 1a, item 3.

[0021]FIG. 5 shows the hemispherical element of the present invention. A hemisphere is comprised of an infinite number of arches rotated in infinitesimally small increments through a full 360°, item 2.

[0022]FIG. 6 shows a pallet deck of the present invention wherein a plurality of the item 2 hemispheres are imposed upon a base material of suitable mechanical properties such as to provide a force transfer matrix that is placed in compression by the reaction of the load transmitted by direct or indirect contact between the item 2 hemispheres. The force is hence transmitted to item 3, which is the plurality of tubular and/or semi-tubular sections arranged such as to absorb stresses and transmit such stresses to the legs or posts.

[0023]FIG. 7 shows a portion of the plurality of item 2 hemispherical elements imposed upon a suitable structural material and the direct and indirect contact points between the item 2 hemispherical elements.

[0024]FIG. 8 shows a preferred embodiment of the present invention for a standard size 48″ by 40″ pallet. The top deck described above is attached to support legs that provide ground clearance for forklift and/or pallet jack entry.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The first issue in pallet design is strength. A pallet must support the weight of the product or products it stores statically when just loaded and dynamically when the product or products are transported on the pallet assembly. Because a pallet is a planar device, it must also maintain cross-plane integrity, rigidity and stiffness so that opposing corners do not deform or loosen and damage or lose the load. Issues of weight and durability are also important to successful pallet performance as well. Typical general/heavy duty wood alternative shipping pallets presently available weigh 40 to 60 pounds. These excessive weight pallets cost twice the price promised by the present invention. Low weight and low cost is achieved by the present invention because of the innovations in a structural member that provides high strength and rigidity with substantially less material.

[0026] To this end the present invention employs an internal or exoskeleton comprised of a plurality of hollow arch or circular or semi-circular sections arranged at angles relative to each other such as to provide stiffness and rigidity and structural integrity to the planar surface at a much-reduced weight.

[0027]FIG. 1, View a shows a structural element designed in accordance with the elements of the present invention. Item 1 is the complete structural element as a skeleton that is to be imbedded or partially imbedded in a matrix of a material that will provide the form factor of a plastic shipping pallet. Item 2 is a plurality of hollow hemispheres of the present invention the purpose of which is later described. Item 3 shows a plurality of edge terminators in the form of semi-tubular elements formed integral with the hemispherical elements, the purpose of which is later described. View b is a cut-away expanded view of the upper right hand corner of view a showing details of Items 2 and 3. View c is of a completed shipping pallet, shown transparent for clarity, where the structural element of the present invention is embedded into the end product. View d is an expanded view of the upper right hand corner of the end product of view c showing how the matrix fill material used for form factor encases the upper side of the structural element of the present invention. View e shows the completed product.

[0028]FIG. 1 representations of item 2 are of a plurality of hollow domes and are but one possible embodiment of the present invention. Other embodiments, such as a lattice configuration, will be immediately obvious to one skilled in the art. Item 3 is a plurality of semi-tubular terminators wherein the load carried by the pallet is transferred through the hemispherical elements of item 2 to the legs or posts. Representation of this particular embodiment is in no way meant to limit the claims of the present invention; rather, it shows but one method to implement the means and methods thereof.

[0029]FIG. 2 illustrates a conventional post/beam deck type shipping pallet where a bending moment is imposed by virtue of the load or weight of the product being carried. This bending moment creates upper fiber compression and lower fiber tension in a pallet deck or other beam or wall type structural member that is weight or force loaded on one side.

[0030]FIG. 3a shows a full arch element under an applied load. The forces induced by this load are reacted through the arch and offset to the edges parallel to the applied load. In FIG. 3b the arch of the present invention is terminated short of a full radius, and the load is reacted through the arch at an angle relating to the geometry of the section.

[0031]FIG. 4 shows how the connection between any of a plurality of arch sections interact to produce a compressive force counteracting the tensile force normally encountered in a loaded beam section.

[0032]FIG. 5 shows the hemisphere of the present invention, item 2. A hemisphere is an infinite number of infinitesimally small arches rotated in infinitesimally small increments through a full 360°. The reaction to forces is the same as in the arches of FIG. 4 but the reaction is absorbed and rotated through the full 360°.

[0033]FIG. 6 shows the item 2 hemispherical elements as they react to the transmitted forces of the pallet deck to the tubular or semi-tubular elements shown as item 3. Item 3 elements are arch sections within the scope of the present invention but other geometric shapes are possible, as will be immediately obvious to one skilled in the art and are not by reference excluded.

[0034]FIG. 7 shows several of the plurality of item 2 hollow hemispherical elements impressed into a sheet of suitable structural element to form the internal skeleton of the pallet. The interaction of the force redirection is shown for both direct hemisphere four point edge contact and for indirect contact through the structural material in which the hemispheres are impressed. The tubular or semi-tubular edge elements may also be impressed into the structural material to complete the stress transfer.

[0035]FIG. 8 shows a typical pallet with the internal skeleton of the present invention and the addition of lightweight filler material to add necessary form to the product.

[0036] The present invention lends itself to a wide variety of materials and manufacturing processes. The essential components may be made of the same or a composite of different materials and may incorporate more than one material within the manufacture of any one component. Component pieces of the present invention may be produced in plastic type materials, metallic elements, or any combination thereof or from any material having sufficient strength and rigidity to prove acceptable in the application.

[0037] The load bearing structure for a typical shipping pallet illustrated and described herein is the preferred embodiment of the present invention. However, the preferred embodiment is but one of many applications for the technology of the present invention that are immediately obvious to one skilled in the art. Nothing herein is meant in any way to limit the present invention or the technology of the present invention to shipping pallets or any other application for this technology. All such other implementations and applications, not shown here for simplicity, are deemed to be within the scope of the present invention, and are to be limited only by the claims appended hereto. 

In view of the above, I claim: 1) A load bearing structure comprised of arch elements placed adjacent to each other wherein tensile stresses, induced by a bending moment imposed upon on the structure from an applied load, are canceled or partially canceled by virtue of the arch elements' direct or indirect interference with adjacent elements, which place the material of construction into compressive stress and create an offsetting or partially offsetting compressive force within and between the elements. 2) A load bearing structure comprised of a plurality of arch elements rotated through some finite angle arranged so as to directly or indirectly contact adjacent like elements of some finite angle in order to place the material of construction into compressive stress canceling or partially canceling tensile stresses induced by a bending moment imposed upon the structure by an applied load. 3) The elements of claim 1 wherein a plurality of said structural elements are extended longitudinally or laterally or both to create a large weight bearing surface area. 4) The elements of claim 1 wherein the arch elements are rotated through a lesser angle than 360°. 5) The elements of claim 1 wherein the arch elements are oriented perpendicular to the imposed load. 6) The elements of claim 1 wherein the arch elements are oriented parallel to the imposed load. 7) The elements of claim 1 wherein the arch elements are oriented other than parallel or perpendicular to the imposed load. 8) The elements of claim 1 wherein the arch elements are oriented randomly in relation to the imposed load. 9) The elements of claim 2 wherein a plurality of said structural elements are extended longitudinally or laterally or both to create a large weight bearing surface area. 10) The elements of claim 2 wherein the arch elements are rotated through a lesser angle than 360°. 11) The elements of claim 2 wherein the arch elements are oriented perpendicular to the imposed load. 12) The elements of claim 2 wherein the arch elements are oriented parallel to the imposed load. 13) The elements of claim 2 wherein the arch elements are oriented other than parallel or perpendicular to the imposed load. 14) The elements of claim 2 wherein the arch elements are oriented randomly in relation to the imposed load. 